Soil weed seed bank is an important factor determining above-ground floristic composition and weed density in agricultural systems. The quantitative and qualitative measures of weed seed bank can help growers to predict the extent to which they are facing weed problems. Along with tillage, crop residues can affect the fate of weeds in the upcoming crops. To investigate such effects, we compared the effects of tillage systems [conventional tillage (CT), reduced tillage (RT), and no tillage (NT)], wheat residue retention, and nitrogen (N) rates (0, 69, 138, and 207 kg N ha⁻¹) on depth-related characteristics of the weed seed bank under a sweet corn-wheat sequence during 2014–2015 growing seasons in Shiraz, Iran. Soil bank was not affected by tillage systems but tended to be slightly higher under RT. The highest (898 seeds m⁻²) and lowest (322 seeds m⁻²) weed population at 0–10 cm depth were found when 138 kg N ha⁻¹ in 2015 and 207 kg N ha⁻¹ in 2014 were applied. Species richness and diversity were higher under NT and RT practices at the top layer, but CT system was more diversified at deeper depths. They were higher when crop residues were retained as well. Barnyard grass (Echinochloa crus-galli [L.] Beauv), common lambsquarter (Chenopodium album L.), common purslane (Portulaca oleracea L.), field bindweed (Convolvulus arvensis L.), flixweed (Descoreinia sofia [L.] Webb. & Berth.), henbit (Lamium amplexicaule L.), pigweeds (Amaranthus spp.), and stinking goosefoot (Chenopodium vulvaria L.) were the most common weeds found in all tillage systems and soil depths. Grasses were relatively lower than broadleaves regardless of treatments. Weed seed bank was mostly affected by weather conditions than treatments in this short-term experiment.

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伊朗甜玉米-小麦轮作中耕作、残茬和施肥管理对杂草种子库的影响

土壤杂草种子库是决定农业系统地上植物区系组成和杂草密度的重要因素。杂草种子库的定量和定性测量可以帮助种植者预测他们面临杂草问题的程度。与耕作一起，作物残留物会影响即将到来的作物中杂草的命运。为了研究这些影响，我们比较了耕作系统 [常规耕作 (CT)、减耕 (RT) 和免耕 (NT)]、小麦残渣保留和氮 (N) 率的影响（0、69、138、和 207 公斤 N 公顷^-1) 在 2014-2015 年伊朗设拉子生长季节期间甜玉米-小麦序列下杂草种子库的深度相关特征。土壤库不受耕作系统的影响，但在 RT 下往往略高。^{当 2015 年施用 138 kg N ha -1}和2014 年施用207 kg N ha ^-1时，0-10 cm 深度的杂草种群数量最高（898 颗种子 m ^-2）和最低（322 颗种子 m ^{-2 ）。}在顶层的 NT 和 RT 实践下，物种丰富度和多样性更高，但 CT 系统在更深的深度更加多样化。当作物残茬也被保留时，它们会更高。稗草（Echinochloa crus-galli [L.] Beauv），普通羊角草（Chenopodium albumL.)、普通马齿苋 ( Portulaca oleracea L.)、野生旋花 ( Convolvulus arvensis L.)、flixweed ( Descoreinia sofia [L.] Webb. & Berth.)、马齿苋 ( Lamium amplexicaule L.)、藜 ( Amaranthus spp.) ), 和臭藜 ( Chenopodium v​​ulvaria L.) 是所有耕作系统和土壤深度中最常见的杂草。无论处理如何，草都相对低于阔叶植物。在这个短期实验中，与处理相比，杂草种子库主要受天气条件的影响。